[LeetCode 258] Add Digits

最新推荐文章于 2022-04-28 10:39:31 发布

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本文提供了一种高效的算法，用于将任意非负整数连续加总其各位数字，直至结果为一位数。同时探讨了在不使用循环或递归的情况下实现这一目标的可能性，并给出了具体实现代码。

Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.

For example:

Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.

Follow up:

Could you do it without any loop/recursion in O(1) runtime?

Solution:

1. 逐位相加直到小于10

public int addDigits(int num) {
        while(num>=10){
            num = (num/10)+num%10;
        }
        return num;
    }

通过输入距离来发现规律

123456789 10 11 12 13 14 15

123456789 1 2 3 4 5 6

public int addDigits(int num) {
        return 1 + (num-1)%9;
    }